1. Field of the Invention
The invention relates to a spring support having an axially movable spring plate, an actuator including a rotor and a stator, force-transmitting element which moves axially in response to rotation of the rotor, and a spring plate fixed to the force transmitting element.
2. Description of the Related Art
WO 02/055326 describes a vehicle suspension in which a vibration damper has an axially adjustable spring plate. An electric motor having an external stator and an internal rotor, the rotational movement of which is translated into an axial movement by a movement converting device in the form of a threaded spindle, serves as actuator. The inner side of the rotor and an outer side of a sleeve-shaped extension of the axially moveable spring plate form the threaded spindle.
In order to fulfill the function of a threaded spindle it is necessary that the spring plate be incapable of performing a rotational movement. Two possible ways of achieving this are proposed. On the one hand it is described how the vehicle suspension spring acts to brace the torque in opposition to the drive torque of the electric motor. A circumferential force is thereby introduced into the vehicle suspension spring about its longitudinal axis. It is to be feared that in addition to the forced vibration emanating from the sprung wheel, a second vibration also acts on the vehicle spring, namely that resulting from the torque bracing of the spring plate in opposition to the drive torque of the electric motor.
As an alternative it is stated that the spring plate can also be torsionally locked by bracing against the vehicle body. The dome for attaching the spring strut to the vehicle body is singled out as being a particularly suitable point. On closer examination, however, it will be noted that producing a torsional safeguard, such as a crease in the dome, is very difficult. Furthermore fitting the spring plate into a torsional safeguard of the spring plate is a laborious task, since direct visual sighting of the outside of the spring plate and the inside wall of the dome is obscured by the annular electric motor.